I don't know about calories, but I find instant oatmeal just doesn't give me enough energy for the day. I add a bunch to it (quinoa flakes, sugar, whole milk powder, dried cranberries, sunflower seeds, pumpkin seeds, current raisins, brown sugar) and increase the portion to about 750 mls. That keeps me going.
My favourite, though, is macaroni with alfredo sauce! I cut sausage into the mix to get fat and protein. It takes a few minutes longer to cook but keeps me going.
What about lunch? Lunch foods are so heavy and they get boring. I added chocolate covered espresso beans to my trail mix and that was a definite improvement, but I hope to avoid eating another granola bar or fruit bar.